This invention relates to a double acting (or double coil) electromagnetic valve wherein the basic concept disclosed in my Japanese Patent No. 479023 (Patent Publication No. 1264/1966) is used in combination with new concept of positively utilizing residual magnetism.
Double acting electromagnetic valves, which are also referred to as double solenoid-operated electromagnetic valves, are widely known. A typical construction of these valves comprises two electromagnets including two magnetic cores and two coils. When one of the coils is energized, the electromagnetic valve is transferred from a normal operating position to another operating position and held at this position even after the coil has been deenergized. When it is desired to set the valve back to the normal operating position, another coil must be energized. The valve thus set back to the normal operating position is held at the normal operating position, even after the second coil has been deenergized, until the first coil is energized.
The electromagnetic valve of this type has the advantage that it inhibits spontaneous transfer of the valve in the case of, for instance, power failure. However, the construction of the valve is complicated because of the two electromagnets provided separately, and the size thereof is comparatively great.